U.S. patent number 4,075,097 [Application Number 05/564,111] was granted by the patent office on 1978-02-21 for oil filter with oil improving dissolving body.
This patent grant is currently assigned to Monroe Auto Equipment Company. Invention is credited to George A. Paul.
United States Patent |
4,075,097 |
Paul |
February 21, 1978 |
**Please see images for:
( Certificate of Correction ) ** |
Oil filter with oil improving dissolving body
Abstract
An oil filter is disclosed as having a filter enclosure provided
with oil inlet and outlet ports adapted for communication with the
oil circulating system of an associated oil lubricated engine.
Disposed within the enclosure is a filter element fabricated of any
suitable filtering media. In addition to the filter element, a body
of an oil soluble, relatively solid polymer having oil additives
compounded therein is disposed within the enclosure. The polymer
body is located within the enclosure so as to be in an area where
minimum oil flow occurs, i.e. in a relatively non-turbulent oil
flow area, which results in the polymer dissolving at a relatively
uniform or linear rate so as to prevent undesirable concentrations
of the additives during the effective service life of the filter.
If desired, suitable baffle means may be interposed between the
area of primary oil flow within the filter and the oil soluble
polymer, whereby to provide for the controlled contact of the flow
of turbulent oil within the filter with the polymer body and
thereby assure the desired linear or uniform rate of polymer
dissolution.
Inventors: |
Paul; George A. (Midland,
MI) |
Assignee: |
Monroe Auto Equipment Company
(Monroe, MI)
|
Family
ID: |
24253193 |
Appl.
No.: |
05/564,111 |
Filed: |
April 1, 1975 |
Current U.S.
Class: |
210/167.02;
210/DIG.17; 210/209; 422/261; 210/199; 210/206; 210/501 |
Current CPC
Class: |
B01D
27/08 (20130101); B01D 37/025 (20130101); B01D
27/106 (20130101); B01D 27/103 (20130101); Y10S
210/17 (20130101); F01M 2001/1014 (20130101) |
Current International
Class: |
B01D
37/00 (20060101); B01D 37/02 (20060101); B01D
27/08 (20060101); B01D 035/00 (); C10M
007/10 () |
Field of
Search: |
;210/117,130,131,136,501,502,506,507,209,167,168
;252/9,10,11,56R,59,199,206 ;23/267B,267D,272 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Smalheer, Smith, Lubricant Additives, 1967, The Lezius-Hiles Co.,
Cleveland, Ohio..
|
Primary Examiner: Hart; Charles N.
Assistant Examiner: Therkorn; Ernest G.
Attorney, Agent or Firm: Harness, Dickey & Pierce
Claims
I claim:
1. An oil filter for an engine having a circulating oil lubrication
system,
said filter including an enclosure having a generally
cylindrically-shaped side wall and having an annular ring-shaped
filter element located concentrically therein,
a base plate at one end of said enclosure having a generally
centrally located oil outlet opening and at least one oil inlet
opening spaced radially from said outlet opening,
said filter being of the spin-on type and adapted to have said base
plate mounted on a support structure having a mounting element
threadably receivable within said outlet opening of said base
plate,
a first oil passage within said enclosure and located between the
inner periphery of the side wall of said enclosure and the adjacent
portion of the outer periphery of said filter element communicating
said oil inlet opening with the entire axial length of said
adjacent portion of the outer periphery of said filter element,
a second oil passage within said enclosure communicating the inner
periphery of said filter element with said oil outlet opening, an
annular body located at a position at the opposite end of said
enclosure from said base plate and being substantially axially
aligned with said filter element, said body being fabricated of a
material having oil improver properties and which is capable of
going into solution in the oil when the oil comes in contact
therewith, said position of said body being such that oil must flow
axially along the entire length of the outer periphery of said
filter element before said oil reaches said annular body, with the
result that said body is located where relatively limited amount of
oil movement occurs, whereby said polymer body will be
substantially unaffected by the mechanical movement of oil within
said enclosure and will dissolve into the oil at a relatively
uniform rate over the normal service life of the oil and thereby
assure against over and underdosing of the improver properties
being replenished into the oil in said system by dissolution of
said polymer.
2. An oil filter as set forth in claim 1 wherein said filter
element is fabricated of pleated paper-like material.
3. An oil filter as set forth in claim 1 which includes valve means
for controlling oil circulation within said filter.
4. An oil filter as set forth in claim 3 wherein said valve means
comprises anti-drainback valve means.
5. An oil filter as set forth in claim 3 wherein said valve means
comprises pressure relief valve means.
6. An oil filter as set forth in claim 1 wherein said body is
fabricated of a high molecular weight polymer that is slowly
dissolvable in oil.
7. An oil filter as set forth in claim 6 wherein said body is
fabricated in polyisobutylene.
8. An oil filter as set forth in claim 7 wherein said body has an
extreme pressure additive compounded therein.
9. An oil filter as set forth in claim 7 wherein said body has a
corrosion inhibitor additive compounded therein.
10. An oil filter as set forth in claim 7 wherein said extreme
pressure additive comprises zinc dibutyldithiocarbomate.
11. An oil filter as set forth in claim 7 wherein said body has a
phenolic-type anti-oxidant additive compounded therein.
12. An oil filter as set forth in claim 11 wherein said
anti-oxidant additive comprises 4,4'-methylenebis
(2,6-di-tert-butylphenol).
13. An oil filter as set forth in claim 1 wherein said body is of a
generally ring-shaped configuration and comprises radially inner
and outer sides, wherein said filter element is fabricated of
pleated paper and has the radially inner and outer sides thereof
generally axially coincident with the radially inner and outer
sides of said body, and wherein said body is fabricated of a
thermoplastic polymer. (comprising polyisobutylene having Butyl
Zimate and Ethyl-702 compounded therein)
14. A spin-on type oil filter for an engine having a circulating
oil lubrication system,
said filter including an enclosure having a generally
cylindrically-shaped side wall and having an annular ring-shaped
filter element concentrically located therein and oil inlet and
outlet ports communicable with the lubrication system of the
engine,
said filter element defining a generally central chamber which is
coextensive of the axial length thereof and the periphery of which
comprises the outlet side of said filter element,
an oil soluble, relatively solid body having oil improver
properties,
means defining first and second fluid flow paths along which oil
flows within said enclosure, said first path being located in part
between the inner periphery of said enclosure side wall and the
entire axially extending outer periphery of said filter element and
communicating said inlet ports with said axially extending outer
periphery of said filter element which comprises the inlet side
thereof, said second path communicating said outlet port with said
chamber and said outlet side of said filter element,
said body being fixedly located at a position within said chamber
and adapted to be contacted by oil flowing along said second flow
path, with said position of said body being such that said element
is out of direct impingement of oil entering said enclosure through
said inlet so that a minimum distrubance of the concentration
gradient between the oil and said body occurs as oil circulates
through said filter, whereby said body will dissolve into the oil
at a relatively uniform rate over the service life of the oil and
whereby any mass portion of said body that becomes separated from
the main body thereof will be prevented from migrating into said
lubrication system.
15. An oil filter as set forth in claim 14 wherein said body is
fabricated of a high molecular weight polymer that is slowly
dissolvable in oil.
16. An oil filter as set forth in claim 14 which includes baffle
means interposed within the exterior of said body and the oil
circulating through said oil filter for controlling the magnitude
of contact of said oil with the exterior of said body.
Description
BACKGROUND OF THE INVENTION
As is well known in the art, modern automotive vehicle engines are
produced with circulating oil lubrication systems wherein oil is
forced under pressure by means of the engine driven oil pump from
the oil sump or pan through various lubricating passages to the
critical points of lubrication of the engines. In order to remove
or at least minimize oil contaminants within such engine
lubrication systems, it has been the practice to incorporate oil
filters therein. It is usually the case that such filters are of
the replaceable type and as such, the filter units are periodically
discarded and replaced, usually concurrently with the replacement
of the engine lubricating oils. Generally, oil filters produced and
sold for both original equipment and replacement on automotive
vehicles operate on the same principle; namely, the filter units
are provided with a filtering media or element and under normal
operating conditions, oil enters at the top of the filter through a
series of holes leading to the outer periphery of the filtering
media. The oil then passes through the filtering media during which
the oil contaminants are removed and the oil thereafter passes
centrally through the filter element and exits through an outlet
port, from where the oil is communicated back through the
lubrication system of the vehicle engine. Frequently,
anti-drainback valves are used which prevent the oil from draining
out of the filter after the engine has stopped operating, and in
many instances, the filter units are provided with pressure relief
valves which provide means for bypassing the filter element or
media at such time as a predetermined pressure drop occurs across
the filter element, i.e., when the lubricant is in a highly viscous
state such as during low temperature operating conditions.
In order for the lubrication systems of the aforementioned type of
engines to operate satisfactorily, the lubricant or oil must have
certain properties that insure both adequate system flow and
minimum performance after delivery. At the same time, the oil must
not have any tendency to degrade the life or performance of any
component parts of the vehicle engine with which it comes into
contact. In light of these requirements, several categorical
properties and their acceptable performance levels have been
established. Such properties and performance levels include oil
viscosity, oil oxidation rate, anti-wear properties, detergent and
dispersant properties, and anticorrosion properties. More
particularly, engine oil used in modern automotive, as well as
light truck, engines are specified by two separate classifications.
The first is the engine service classification and relates
primarily to the performance of the engine oil under simulated
service operating conditions. Typical requirements are a maximum
increase in viscosity which would indicate the presence of
contaminants in the engine after certain sequential operations, the
presence of scuffing and actual wear of certain parts of the oil
testing apparatus (typically a specified type of engine), and the
presence of other deposits, such as varnish and the like on engine
piston rings. The second classification is based on the viscosity
of the oil at 0.degree. F. and at 210.degree. F., and engine oils
are normally rated at either the 0.degree. F. point, the
210.degree. F. point or at both. For example, a typical
specification would be 10W indicating a performance level only at
0.degree. F.; 30 indicating a performance level only at 210.degree.
F. or 10W30 indicating minimum performance levels at both 0.degree.
F. and 210.degree. F.
Producers of engine oils have found that in order to meet the
aforesaid service classifications, petroleum oils by themselves are
unsuitable. Consequently, a typical engine lubricating oil contains
between 10% and 20% additives or non-oil components, in order to
meet these classification requirements. Typical components needed
to meet the service classification are detergents, dispersants,
inhibitors, anti-wear agents and anticorrosive agents. Those
lubricants of the multiple viscosity or multi-grade type require an
additive or component in them to provide for acceptable performance
at the requisite viscosity levels. Such additives or components are
known in the art as viscosity improvers or viscosity index (VI)
improvers. Unfortunately, however, many of the additive components
of modern engine oils degrade with use, either because of (a)
inherent deficiencies, or (b) because their function is, in fact,
to be consumed or depleted to provide the necessary or desired
feature in the lubricant. More particularly, oil viscosity
improvers fall into category (a) since they consist of very large
molecules which break up during use so that they can no longer
perform their intended function. This breaking up of the VI
molecules is referred to as shear-instability, which results from
the fact that the molecules are unstable when subjected to high
fluid shear rates. In the second category (b) are those types of
oil additives which are sacrificed or which are purposely consumed
during the service life of the oil. Examples of such sacrificial
additives are anti-oxidants which function to prevent the
deterioration associated with oxygen attack on the lubricant base
fluid. Normally, anti-oxidants are provided in the oil for the
purpose of absorbing any oxygen present and thus, among other
things, such additives prolong the resistance of the oil to form
sludge. Over the service life of the oil, however, the anti-oxidant
additives become saturated and hence the resistance of the oil to
form sludge gradually terminates. Anti-wear and anti-corrosive
additives or compounds are similar to anti-oxidants in that these
additives are intended to be deposited on the engine surfaces.
Because of the washing action of the oil and the rubbing of the
metal surfaces during operation of the engine, however, such
deposits do not remain on the critical surfaces and must be
replenished at these points from the lubricant. When the
concentration of these additives drops below a certain level, the
additives can no longer be depositive and hence the engine
components are subject to wear and corrosion.
In view of the finite life of the lubricant additives which are
utilized in modern engine oils, either because of the inherent
deficiencies of such additives or because of their depletion
(sacrificial) characteristics, it has heretofore been proposed to
replace or replenish such additives and thereby extend the service
life of the engine oils. The prior art is replete with a myriad of
different ways of effecting such replacement of engine oil
additives, and among such prior art teachings are those methods
disclosed in the below discussed United States patents which, while
being related to the subject matter of the invention disclosed
herein, are not believed to be anticipatory of the applicant's
inventive concepts as defined in the claims appended hereto.
U.S. Pat. No. 2,302,552, for Method and Apparatus for Treating
Lubricant Oils, discloses a way of replenishing lubricating oil
additives by impregnating an absorbant material, such as the filter
material, with a sparingly soluble additive compound such that the
passage of lubricating oil through the filter media effects a
progressive dissolution of the additives therein. The absorbant
material itself is insoluble in the oil.
U.S. Pat. No. 2,310,305, for Method and Means for Purifying
Lubricants, discloses a system for effecting a continuous
replenishment of additive agents in a recirculating engine oil
system by providing a separate reservoir or chamber, and preferably
utilizing the oil filter itself for incorporating additive agents
of low solubility which are contacted by the oil passing through
the reservoir or filter to effect a progressive dissolving thereof.
It is suggested in this patent that fine particles can be loaded
within the filter cartridge or the material of which the filter
cartridge is comprised can be coated with the additive substance.
Alternatively, or in conjunction with the foregoing, a solid or
semi-solid or porous mass of the material or of an inhibitor
impregnated inert material may be positioned within the filter
chamber so as to be continuously contacted by the oil passing
therethrough.
U.S. Pat. No. 2,435,707, for Method and Apparatus for Treating Oil,
discloses a system for maintaining the effectiveness of the
detergent additives present in engine lubricating oils by
continuously adding to the lubricant oil an amino soap additive
which is very slightly soluble in the oil so as to cause an
agglomeration of the detergent suspended colloidal dirt particles
in the oil in order that they attain a size in which they can be
removed by the filter.
U.S. Pat. No. 2,898,902, for Apparatus for Supplying Additives to
Lubricating Systems, discloses a mechanical metering system for
effecting a periodic replenishment of the additives. The metering
system is actuated on a time basis or other cycle, such as, for
example, each time the engine is started, whereby a metered
quantity of an additive or blend of additives is injected into the
crankcase of the vehicle engine.
U.S. Pat. No. 2,943,737, for Filter and Method of Purifying Oil,
discloses an oil filter in which the filter medium is coated with a
thermoplastic resin selected from the group consisting of
polyethylene glycol and polypropylene glycol. While the obstensible
purpose of the coating is to improve filtering efficiency,
apparently some of the polyglycol resin does dissolve and evidently
does have a detergent boosting affect.
U.S. Pat. No. 3,314,884, for fuels and Lubricants Containing
Inclusion Compounds. This patent discloses a technique for
supplying active chemical additives to a lubricating oil
composition. A release of the additive is achieved by any mechanism
which destroys a framework of a surrounding inclusion or housed
compound and such techniques include melting, dissolving or other
disintegrating of the structure of the housed compound.
U.S. Pat. No. 3,749,247, for Addition of Oxidation Inhibitor to
Lubricating Oil, discloses a system for replenishing the additives
in crankcase motor oils, and in particular, anti-oxidants in the
oil, by placing plastic containers composed of polyolefin materials
which are filled with liquid additive compounds and are positioned
within gaps between the filter element flutes. The additive
compound passes through the walls of the container by diffusion at
a rate consistent with the need for replacing the anti-oxidant
additive in the oil.
All of the various concepts disclosed in the aforementioned
patents, while generally addressing themselves to the problems
resulting from oil additive depletion, are subject to various
objectionable criticisms, due primarily to the complexity of the
systems and methods proposed therein and the resultant difficulties
of adapting such proposed systems in commerically acceptable filter
units. Additionally, such proposed systems are seen to be
objectionable from the standpoint that there is no single system or
method proposed therein which provides for the replenishment of the
three most important oil additives which become depleted throughout
the service of the oil, namely, the viscosity index improvers,
anti-oxidants, and anti-wear-anti-corrosion compounds. Moreover,
such heretofore proposed systems suffer the extremely important
shortcoming of not assuring against over or underdosing of the
additives, a characteristic which can be as detrimental to the
engine oil and engine component parts as the depletion of the
original oil additives. For example, if the engine oil is provided
with an overdose of a VI improver, there is a marked reduction in
the low temperature performance of the oil which in turn results in
engine starting difficulties at low operating temperatures.
U.S. Pat. No. 3,336,223, for Method and Means for Maintaining An
Effective Concentration of Additives in Oil, discloses a system for
prolonging the useful life of lubricating oils and is believed to
disclose a system which overcomes many of the objectionable
characteristics of the various systems described in the
aforementioned patents. In particular, the system set forth in the
U.S. Pat. No. 3,336,223 patent contemplates providing a oil soluble
solid thermoplastic polymer within an oil filter enclosure and
impinging the polymer with the circulating oil, whereby oil
additives which are compounded into the polymer will be gradually
dispersed into the oil. In spite of the many advantages that the
system disclosed in the U.S. Pat. No. 3,336,223 patent has over the
prior art, this patent falls short at least in one important
respect of teaching an additive replenishing system that provides
for the optimum rate of additive replenishment during the service
life of the oil, and this particular shortcoming has been found to
be extremely critical in assuring optimum effective oil life. In
particular, it has been found that optimum oil life is achieved in
those cases wherein the oil additives are replenished at a
relatively uniform or linear rate so as to thereby replenish the
original oil additives at essentially the same rate as they become
depleted, thus positively assuring against over or underdosing of
the additives. In accordance with the present invention, it has
been discovered that in order to provide for a linear or constant
rate of additive replenishment, it is imperative that the polymer
body having the oil additives compounded therein be located at an
area within the associated filter enclosure wherein a minimum
amount of oil circulation occurs, i.e., a relatively stagnant oil
circulating area. By so locating the polymer-additive compound,
consistently uniform and linear dispersion or dissolution of the
polymer compound will occur, thereby assuring for a linear
replenishment of the additives over the desired service life (i.e.,
between drain intervals) of the engine oil, as will be hereinafter
described in detail.
SUMMARY OF THE INVENTION
This invention relates generally to oil filters and, more
particularly, to a new and improved filter incorporating an oil
soluble thermoplastic polymer having oil additives compounded
therein and located within the oil filter at a position so as to
assure for a relatively linear rate of dissolution of the
polymer.
It is accordingly a general object of the present invention to
provide a new and improved oil filter of the above described
type.
It is a more particular object of the present invention to provide
a new and improved oil filter which assures against over or
underdosing of the additives which are being replaced upon
dissolution of the polymer.
It is still a more particular object of the present invention to
provide a new and improved oil filter unit of the above described
type wherein the polymer is disposed with an area of the oil filter
housing wherein relatively no turbulent oil flow occurs.
It is a further object of the present invention to provide a new
and improved oil filter unit of the above described type which may
be provided with baffle means to assure against turbulent oil
flowing in direct contact with the thermoplastic polymer in the
filter enclosure.
It is yet another object of the present invention to provide a new
and improved filter unit, as above described, which uses many parts
of conventional filters so as to require a minimum amount of stock
filter modification.
It is another object of the present invention to provide a new and
improved oil filter unit that will find universality of application
in that the principles of properly locating the thermoplastic oil
soluble polymer in a relatively stagnant oil flow area may be
applied to valveless filter units or those filter units having
anti-drainback and/or pressure relief valves.
It is a further object of the present invention to provide a new
and improved filter unit of the above described type wherein the
oil soluble thermoplastic polymer is preferably, although not
necessarily, located upstream of the filter element so as to assure
against any polymer migration into the lubrication system of the
associated engine.
It is yet another object of the present invention to provide a new
and improved filter unit of the above described type which may be
economically manufactured and will have a long and effective
operational life.
Other objects and advantages of the present invention will become
apparent from the following detailed description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a transverse cross sectional view of a vehicle engine
filter embodying the principles of the present invention
therein;
FIG. 2 is an enlarged fragmentary cross sectional view taken
substantially along the line 2--2 of FIG. 1;
FIG. 3 is an enlarged fragmentary view of a portion of a filter
unit similar to the construction shown in FIG. 1 but without the
anti-drainback and pressure relief valves incorporated therein;
FIG. 4 is an enlarged fragmentary cross sectional view of an
alternate embodiment of the filter design of the present
invention;
FIG. 5 is an enlarged transverse cross sectional view of yet
another embodiment of the filter design of the present
invention;
FIG. 6 is a transverse cross sectional view of still a further
embodiment of the present invention, and
FIG. 7 is a graphic representation of the effect that a
thermoplastic polymer utilized in accordance with the teachings of
the present invention has an oil circulating in a typical
lubrication system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in detail to the drawings and in particular to FIG. 1
thereof, a filter unit in accordance with one preferred embodiment
of the present invention is generally designated by the numeral 10
and is shown as comprising an annular housing or enclosure 12
having an annular side wall section 14 and a generally dome-shaped
end section 16. The side wall section 14 is formed with a plurality
of wrench-engaging faces or facets 18 and the lower open end of the
enclosure 12 is provided with an annular closure plate 20 which is
secured to the annular side wall 14 by means of a suitable rolled
seam or the like 22. The closure plate 20 is formed with an annular
recess 24 which is defined by radially spaced wall portions 26, 28
and an axially disposed wall portion 30. Disposed within the
annular recess 24 is a fluid seal 32 which is adapted for sealing
engagement with a suitable portion of an associated engine block
shown in phantom lines in FIG. 1 and designated by the numeral
34.
Secured to the interior side of the closure plate 20 is an annular
base plate, generally designated by the numeral 36. The base plate
36 comprises a generally radially extending portion 38 which is
secured, as by spot welding or the like, to the closure plate 20,
as best seen at 40. The base plate 36 is formed with a plurality of
circumferentially spaced, axially extending inlet ports 42 and with
a central axially extending flange 44 having an internally threaded
inner periphery 46 defining an oil outlet port 48. As will be
appreciated by those skilled in the art, the filter unit 10 is
secured to the associated engine block 34 by being threadably
received upon a suitable stand pipe or the like (not shown) which
is threaded into the outlet port 48.
Disposed interiorly of the enclosure 12 is an annular filter
element, generally designated by the numeral 50, which may be
fabricated of any suitable filter media and is representatively
illustrated herein as being fabricated of pleated filter paper
which is folded in a manner so as to provide a plurality of pleats
or flutes, best seen in FIG. 2 and generally designated by the
numeral 52. The filter element 50 is disposed between a pair of
axially spaced end caps 54 and 56 which close the axially opposite
ends of the flutes 52 so as to assure that oil circulating through
the unit 10 will pass radially through the filter element 50.
The filter unit 10 is provided with an anti-drainback valve,
generally designated by the numeral 58, which is of a generally
disc or ring-shaped configuration and is fabricated of a suitable
oil impervious elastomeric material, such as synthetic rubber or
the like. The valve 58 is concentrically oriented relative to the
oil outlet port 48 and has the inner periphery thereof retained
against the interior side of the base plate 36 by means of a
generally axially extending section 62 of an annular support flange
64. The flange 64 includes a radially extending portion defining a
plurality of circumferentially spaced axially extending oil bypass
ports 66.
The filter unit 10 is also shown as being provided with a pressure
relief valve, generally designated by the numeral 68, which is
fabricated of a suitable elastomeric material and is of a generally
ring or disc-shaped configuration, as shown in FIG. 1. The valve 68
is located adjacent one side of a support disc or ring 70 which is
adapted to be urged under the influence of a coil spring 72 toward
a pair of concentric valve seats 74 defined by the support flange
64, whereby the relief valve 68 will be sealingly engaged with the
seats 74 and hence block oil flow through the ports 66. Disposed
interiorly from the relief valve 68 is a generally cupshaped spring
retainer 76 which is formed with a central opening and is provided
with a generally radially arranged securing flange 80 that extends
around the outer periphery of the support flange 64.
As is conventional in the art, at such times as the associated
engine is operating, oil will be circulated by the engine oil pump
through the lubrication passages of the engine and will be
communicated through the inlet ports 42 and then radially outwardly
around the outer periphery of the filter element 50. The oil will
then pass radially inwardly through the filter element 50 and be
filtered thereby, after which time the oil will pass axially
through the opening 78 and thereafter through the outlet port 48
back to the engine. When the engine is not operating, the
anti-drainback valve 58 is disposed in the position shown in FIG.
1, with the outer periphery of the valve 58 being movable axially
away from the base plate 38, whereby to permit the aforesaid
circulation of oil through the filter element 50, and at such time
as the engine is shut off, the valve 58 will again seat against the
base plate 36 to prevent any oil within the unit 10 from draining
back into the engine. The pressure relief valve 68 is normally
seated against the valve seats 74; however, at such times as the
filter element 50 becomes clogged or for some other reason that an
excessive pressure differential exists between the inlet ports 42
and outlet port 48, the valve 68 will move axially against the
resistance of the spring 72, whereupon oil entering through the
inlet ports 42 will be circulated through the bypass ports 66 and
thereafter be returned through the outlet port 48 to the engine,
thus circumventing circulation through the filter element 50.
In accordance with the principles of the present invention,
disposed between the dome-shaped section 16 of the enclosure 12 and
the end cap 54 of the filter element 50 is a generally ring-shaped
or annular additive body, generally designated by the numeral 82.
The additive body 82 is formed with a central annular opening 84
adapted to nestingly receive a central portion 86 of a retaining
plate, generally designated by the numeral 88, which is disposed
between the body 82 and the enclosure section 16. The retaining
plate 88 is provided with a generally axially extending annular lip
90 which extends around the outer periphery of the body 82 and a
suitable spring element 92 is provided interjacent the retaining
plate 88 and the enclosure section 16 for resiliently urging the
entire assemblage consisting of the plate 88, body 82, filter
element 50 and end caps 54, 56 toward the base plate 36, whereby to
assure against any undesirable movement of these components within
the enclosure 16.
The additive body 82 may consist of any one of a variety of high
molecular weight polymers that are slowly dissolvable in oil and
which are suitable to have the desired oil additives compounded
therein, whereby when the oil contacts the additive polymer
composition, the polymer will have a low rate of dissolution in the
oil and will thereby be slowly dissolved and/or dispersed into the
oil. If the particular additives which are compounded into the
polymer are oil soluble, such additives will dissolve slowly in the
oil, that is, at essentially the same rate as the polymer itself.
On the other hand, if the additives are oil insoluble when exposed
to the oil, they will be carried along with the oil to perform
their intended function. The polymer thus serves two essential
purposes; it is the carrying medium for the additives and it also
protects the additives from immediate contact with the oil.
Accordingly, the polymer must be a thermoplastic polymer having a
low rate of dissolution in oil and be of a sufficiently high
molecular weight so that the polymers and consequently the
polymer-additive composition, is solid at the temperature of oil
contact, or at least range in viscosity from a plastic-solid to a
solid.
Virtually any polymer that has the aforesaid properties may be used
in practice in the instant invention such as, for example,
ethylene-propylene copolymers ranging in molecular weight from
200,000 to 300,000; ethylene-ethylacrylate polymers ranging in
molecular weight from 200,000 to 300,000; polypropylene oxide
having a molecular weight of about 500,000; and ethylene-vinyl
acetate copolymer ranging in molecular weight from 200,000 to
300,000. One polymer that has been found to be highly satisfactory
and which is preferred is polyisobutylene ranging in molecular
weight from approximately 60,000 to 135,000, and a preferred
polyisobutylene is identified by the registered trademark VISTANEX
that is manufactured by the Enjay Chemical Company.
The additives which are compounded into the above discussed polymer
can be in liquid or solid form; and as previously mentioned, they
can be oil insoluble, or they can range in oil solubility from
partially to completely soluble. As used herein, the term
"additive" includes all materials which can be compounded or
admixed with the polymer and which in any way impart beneficial
properties to the oil being circulated through the filter unit 10.
It is important to note that the polymer itself will tend to
improve the viscosity properties of the oil as the polymer goes
into solution and hence the polymer per se falls under the
aforementioned definition of additives.
The particular additives to be admixed or compounded with the
polymer will, of course, depend on the type and magnitude of
additive replenishment which is being sought. For example and as
previously described, quality crankcase lubricants contain, for
example, detergent additives such as the metal sulfonates, metal
phenates, metal phosphenates, derivatives of alkenyl succinimides
and the like. Suitable oxidation inhibitors that can be included in
the polymer composition are the metal dithiophosphates and metal
dithiocarbonates. One particular anti-oxidant additive that has
been found to be highly satisfactory and is preferred in the
polymer composition is a phenolic anti-oxidant, 4,4'-methylenebis
(2,6-di-tert-butylphenol) that is commercially available under the
tradename Ethyl 702 manufactured by Ethyl Corporation. Extreme
pressure (EP) and oiliness additives, such as sulfur, metal
naphthenates, phosphate esters and sulfurized hydrocarbons, etc.
may be admixed with the polymer, and one highly satisfactory and
preferred EP additive which also is highly satisfactory as a
bearing corrosion inhibitor is zinc dibutyldithiocarbomate that is
commercially available under the registered trademark BUTYL ZIMATE
manufactured by the R. T. Vanderbuilt Company. Of course,
additional additives may be admixed or compounded with the polymer
and the aforesaid list of such additives is merely intended to be
exemplary, and the particular details of acceptable ways of
compounding or admixing the additives and polymers is described in
the aforementioned U.S. Pat. No. 3,336,223, the contents of which
are incorporated by reference in the descriptive portion of this
specification. Additional exemplary additives and polymer
compositions are also set forth in this patent which may be helpful
in compounding the additive body for use in practicing the present
invention.
In accordance with the principles of the present invention, in
order to provide for the optimum linear or uniform rate of
dissolution of the polymer-additive composition constituting the
additive body 82 over the desired life of the oil, i.e., a drain
interval of between 3,000 and 7,500 vehicle miles, and thereby
assure against over or underdosing of the additives that are
replenishing the original depleted additives in the oil, it has
been discovered that it is extremely important that the body 82 be
located at a position within the enclosure 12 where a minimum
amount of oil circulation or flow occurs, i.e., at a location
wherein the oil within the enclosure 12 is essentially stagnant,
whereby there is virtually the minimum amount of contact of the
turbulent oil with the additive body 82. Thus, it is important in
complying with the present invention that the oil circulating
through the filter unit 10 not in any way impinge directly upon the
body 82 since such direct oil impingement would result in turbulent
circulating oil contacting the body 82 and hence result in an
undesirable and accelerated rate of dissolution of the polymer and
consequential premature release of the additives admixed or
compounded therein. In the one preferred embodiment of the present
invention depicted in FIG. 1 of the drawings, it has been found
that the optimum location for the additive body 82 is at the
opposite end of the enclosure 12 from the inlet and outlet ports
42, 48, respectively, and at the extreme axial end of the annulus
or oil flow area defined between the inner periphery of the side
section 14 of the enclosure 12 and the outer periphery of the
filter element 50. Extensive research and experimentation has shown
that by thus locating the additive body 82 within the enclosure
member 12, a substantially linear or uniform rate of dissolution
occurs, as is graphically illustrated in FIG. 7. More particularly,
FIG. 7 demonstrates the linear rate of dissolution by showing the
uniform rate of increase in the viscosity of a test oil that is
caused by the dissolution of a VI (viscosity improver) in a test
apparatus that does not subject the oil to modes of degradation
found in normal engines, but which duplicates the normal drain
interval by means of controlling flow rates and temperatures. It
will be noted that because of homogenous mixture of the polymer and
additives, all additives are replenished at the same linear rate
that is demonstrated in FIG. 7. Therefore, when the additive body
82 is so located as to be as far away as physically possible from
the areas of turbulent oil flow, the primary object of the present
invention of providing a filter unit wherein there is a uniform or
linear rate of additive replenishment is achieved. It may be noted
that an additional feature of the present invention is accomplished
by locating the additive body 82 in the position shown in FIG. 1 of
the drawings, namely upstream from the filter element 50, which
arrangement assures against any of the polymer body migrating into
the lubrication system of the associated engine in the event any
portion of the body 82 becomes separated therefrom. In other words,
if a part of the body 82 migrates away or is separated from the
main body thereof, such migrating portion will be trapped by the
filter element 50 and thus be prevented from flowing through the
outlet port 48 into the associated lubrication passages or the like
of the engine block 34.
FIGS. 3 through 6 illustrate alternate embodiments of the present
invention and because the various filter units disclosed therein
embody the majority of component parts of the filter unit 10
hereinabove described, such filter units disclosed in FIGS. 3, 4, 5
and 6 will be designated by like numerals with a prime (') suffix,
thereby providing for conciseness of description and affording
unnecessary duplication of reference numerals.
FIG. 3 illustrates a fragmentary portion of a filter unit 10' which
may be identical in construction and operation to the filter unit
10 hereinabove described, with the exception that the unit 10' is
not provided with either an anti-drainback or pressure relief
valve, and it is to be noted that the principles of the present
invention are equally applicable to filter units that are not
provided with such valving arrangements, or are provided with only
one of such valves. In addition, the filter unit 10' has the filter
seal 32' located radially outwardly from the position shown by the
analogous seal 32 of the filter unit 10, thereby rendering the
filter unit 10' adapted for application on certain types of vehicle
engines presently being produced.
Referring now to FIG. 4, a filter unit 10" is shown as comprising
an external housing or casing 12" having a pleated paper filter
element 50" disposed interiorly thereof. The casing 12" is provided
with a base plate 36" at the mounting end thereof, and a suitable
filter seal 32" is located adjacent thereto. The filter element 50'
is retained within the enclosure 12" between spaced apart end caps
54" and 56" and a helical coil spring 100 is interposed between the
end of the enclosure 12" and the adjacent end cap 54" and serves
the same general function as the aforedescribed spring 92 of the
filter unit 10. The enclosure 12" of the filter unit 10" is formed
with a radially outwardly projecting portion, generally designated
by the numeral 102, and comprising axially spaced, radially
extending sections 104 and 106 between which a generally axially
extending side section 108 is arranged. The sections 104-108 define
an annular cavity or chamber 110 within which an annular polymer
body 112 is disposed. The body 112 may be compounded of essentially
the same material as the aforedescribed body 82 or any acceptable
alternative thereof, as hereinabove described. In accordance with
the principles of the present invention, the location of the body
112 is such that a minimum amount of turbulent oil flow or
circulation will occur adjacent thereto, whereby to provide for the
hereinabove described optimum linear or uniform rate of dispersion
of the additives therein. If desired, suitable baffle means may be
interposed between the interior of the enclosure 12" and the
chamber 110 so as to even further limit the amount of contact
between the oil within filter unit 10" and the additive body 112.
It will be noted that the particular axial position of the chamber
110 along the enclosure 12" may be varied, provided, however, that
the position of the chamber 110 is such that the additive body 112
located at an area of low oil circulation consistent with the
principles of the present invention and the advantages hereinabove
described achieved thereby.
FIG. 5 illustrates still another embodiment of the present
invention wherein a filter unit 10'" is shown as comprising a
housing or enclosure 12'" having a filter element 50'" disposed
therein. The filter unit 10'" is essentially of the same
construction and operation as the aforedescribed unit 10", with the
exception that the housing 12'" is not provided with a radially
outwardly extending section 102 and that the end cap 54'" is
provided with a generally centrally located and axially extending
additive body support tube, generally designated by the numeral
114. As shown in FIG. 5, the support tube 114 comprises a generally
annular side wall 116 which is concentrically arranged relative to
the longitudinal axis of the filter unit 10'" and is closed at one
end thereof by a suitable end wall 118. The end of the tube 114
opposite the end wall 118 is provided with a radially disposed
mounting flange 120 which is adapted to be secured by any suitable
manner, such as by spot welding or the like, to the confronting
side of a central portion 122 of the adjacent end cap 54'". The
support tube 114 is formed with a plurality of apertures, generally
designated by the numeral 124, which provides for limited
communication of oil within the filter unit 10'" with a cylindrical
additive body 126 disposed interiorly of the tube 114. The body 126
may be of the same composition as the aforedescribed additive
bodies 112 or 82 and as such is intended to replenish depleted
additives of the oil in the associated circulating lubrication
system. The size of the apertures 124 is selected so as to prevent
polymer migration and such provide minimum contact of the
circulating oil with the additive body 126, whereby to achieve the
desired uniform rate of dispersion of the additives therein, as
discussed above. As an alternative, the tube 114 could be
fabricated of a suitable perforated mesh material of a construction
consistent with the above.
FIG. 6 illustrates still another embodiment of the present
invention wherein a filter unit 10"" is shown as comprising a
filter enclosure 12"" provided with a pleated paper filter element
50"" which is retained between axially spaced end caps 54"" and
56"". Disposed interiorly of the filter element 50"" is a relief
valve assembly, generally designated by the numeral 130 which
includes an annular valve member 132 that is resiliently urged by
means of a coil spring 134 retained within a spring cage 136, with
the valve member 132 normally being engaged with an annular valve
seat 138 extending around the periphery of an opening 140 in a
central portion 141 of the adjacent end cap 54"". At such time as
the pressure around the outer periphery of the filter element 50""
exceeds a predetermined magnitude, the valve member 132 will be
urged axially away from the valve seat 138 against the resistance
of the spring 134, whereby to permit oil to circulate around the
filter element 50"" and through the opening 140 back through the
outlet port 48"" of the base plate 36"". Together with the relief
valve assembly 130, the filter unit 10"" is provided with an
anti-drainback valve 142 which comprises a resilient or elastomeric
disc that is resiliently urged into engagement with the adjacent
side of the base plate 36"" by means of a spring plate 144 having a
plurality of spring fingers 146 engageable with the confronting
side of the end cap 56"". A more detailed description of the
constructon and operation of the relief valve assembly 130 and
anti-drainback valve 142 is given in U.S. Pat. No. 3,395,804,
issued Aug. 6, 1968, for Filter Assembly Relief Valves, the
specification of which is incorporated herein by reference.
In accordance with the principles of the present invention, the
filter unit 10"" is provided with an annular baffle plate 150 which
extends axially within the enclosure 12"" between the interior side
of the base plate 36"" and the dome end section 16"" of the housing
12"" at a position between the radially outer side of the filter
element 50"" and the inner periphery of the enclosure 12"". The
baffle plate 150 defines with the inner periphery of the side of
the enclosure 12"" an annular chamber or annulus 152 which is
communicable with the interior of the enclosure 12"" by means of a
plurality of circumferentially and axially spaced apertures,
generally designated by the numeral 154. Disposed within the
annulus 152 is an annular shaped additive body 156 which is
fabricated of suitable additive compounded polymer as described in
connection with the body 82 or bodies 112 and 126. The purpose of
the baffle plate 150 is to provide for minimum contact of the
turbulent oil circulating through the filter unit 10"" with the
additive body 156, whereby the hereinabove described linear rate of
additive replenishment will be achieved. It is contemplated that
the size and/or number of apertures 154 in the baffle plate 150 may
be varied axially along the length thereof, with a greater number
of apertures 154 being provided at the end of the baffle plate 50
adjacent to the filter end cap 54"", thereby assuring that the
maximum oil contact with the additive body 56 occurs at the
location of the most stagnant oil or minimum oil circulation within
the filter unit 10"", as hereinabove described.
It will be seen from the foregoing that the present invention
provides a novel filter unit wherein through proper placement or
location of the additive-polymer compound or body at a position out
of any direct impingement of oil circulating through the unit and
at a location wherein a minimum amount of contact occurs between
the turbulent oil within the unit and the additive body, uniform or
linear additive dispersion will occur, thereby assuring against
over or underdosing of additives into the oil, and providing for
optimum additive replenishment over the service life of the oil in
the associated lubrication system. As described above, the
aforesaid optimum results may be achieved either through the direct
placement of the additive body at a position of minimum contact
with the oil circulating through the unit, or a suitable baffle
means may be provided interjacent the oil and the additive bodies
so as to provide minimum contact of such oil with the polymer. It
will be appreciated, of course, that the filter units described
hereinabove, while disclosing preferred versions of the present
invention, are intended to be only exemplary insofar as acceptable
designs in achieving the objects hereinabove set forth. It is to be
noted that although the various aforementioned polymer bodies
having central openings and passages formed therein have been
referred to as being "annular," the present invention is not
necessarily intended to be limited to such a construction, since
the principles disclosed herein will find highly satisfactory
application when the polymer body is solid, i.e., is not formed
with any opening or passage. Accordingly, the term "annular," as
used in this specification and claims appended hereto is intended
to be generic to both those types of polymer bodies that are formed
with a central or other type of opening and those bodies of
virtually any shape which are solid or are not provided with any
type of opening or passage whatsoever. Also, it will be appreciated
that various modifications and interchanging of the valve
arrangements shown herein can be made without departing from the
teachings of the present invention. Accordingly, the scope of the
claims appended hereto is in no way intended to be limited to the
specific constructions described herein.
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